What security measures are typically used to protect against TEMPEST attacks against a data center?

TEMPEST (formerly a code word, now a shorthand) refers to studies of compromising emanations, unintentional intelligence-bearing signals which, if intercepted and analyzed, may disclose sensitive information transmitted by data processing equipment. Security measures used to protect against TEMPEST attacks typically focus on reducing or eliminating these compromising emanations. Shielding is a primary defense, involving the use of conductive materials, such as copper or aluminum, to enclose the data center or individual equipment. This shielding prevents electromagnetic radiation from escaping the building. Another common measure is filtering, which involves installing filters on power lines and network cables to block the transmission of compromising signals. Red zones and secure perimeters are established to control access to areas where sensitive data is processed. Strict access controls and monitoring are implemented to prevent unauthorized individuals from bringing electronic devices into the red zone. Equipment is often placed far from the perimeter to increase the difficulty of intercepting signals. Finally, encryption can reduce the risk of intercepted signals being usable because even if signals are captured, they are unreadable without the proper decryption keys. These measures are often implemented in combination to provide a layered defense against TEMPEST attacks.